The effect of falling height on muscle activity and foot motion during landings

The aims of this study were: (a) to examine the effect of falling height on the kinematics of the tibiotalar, talonavicular and calcaneocuboid joints and (b) to study the influence of falling height on the muscle activity of the leg during landings. Six female gymnasts (height: 1.63±0.04 m, weight: 58.21±3.46 kg) participated in this study. All six gymnasts carried out barefoot landings, falling from 1.0, 1.5 and 2.0 m height onto a mat. Three genlocked digital high speed video cameras (250 Hz) captured the motion of the left shank and foot. Surface electromyography (EMG) was used to measure muscle activity (1000 Hz) from five muscles (gastrocnemius medialis, tibialis anterior, peroneus longus, vastus lateralis and hamstrings) of the left leg. The kinematics of the tibiotalar, talonavicular and calcaneocuboid joints were studied. The lower-leg and the foot were modelled by means of a multi-body system, comprising seven rigid bodies. The falling height does not show any influence on the kinematics neither of the tibiotalar nor of the talonavicular joints during landing. The eversion at the calcaneocuboid joint increases with increasing falling height. When augmenting falling height, the myoelectric activity of the muscles of the lower limb increases as well during the pre-activation phase as during the landing itself. The muscles of the lower extremities are capable of stabilizing the tibiotalar and the talonavicular joints actively, restricting their maximal motion by means of a higher activation before and after touchdown. Maximal eversion at the calcaneocuboid joint increases about 52% when landing from 2.0 m.     

Characterization of the azidopine and vinblastine binding site of P-glycoprotein.

To determine the number of drug binding sites that exist on the multidrug transporter, P-glycoprotein, we used azidopine, a dihydropyridine photoaffinity compound that reverses multidrug resistance and labels P-glycoprotein. Azidopine labels P-glycoprotein in two distinct locations: one labeled site is within the amino half of P-glycoprotein between amino acid residues 198 and 440, and the other site is within the carboxy half of the protein. Vinblastine is a cytotoxic drug that is used in cancer chemotherapy and is a substrate for transport by P-glycoprotein. We found that vinblastine inhibits azidopine labeling to approximately the same extent at each labeled site on P-glycoprotein. Because several studies have shown that amino acid residue 185 of P-glycoprotein plays a critical role in some aspects of drug binding and transport, we also studied the effect that amino acid residue 185 has on azidopine labeling. These studies show that azidopine labels both sites equivalently in both wild-type (G185) and mutant (V185) P-glycoproteins. We conclude from our results that the two halves of P-glycoprotein approach each other to form a single binding site for these drugs.     

Acoustical communication by Lipara lucens (Diptera, Chloropidae)

Males of Lipara lucens Mg. living on stems of Common Reed (Phragmites communis Trin.) emit acoustical signals perceived at a distance by a female fly sitting on the same reed stem as vibration of the substrate. Virgin females respond to these signals by vibrating, which in turn elicits searching behaviour in the male fly. It is suggested that this behaviour reduces the time required to find a partner, because a reed stem needs only be visited briefly to ascertain whether a receptive female is present.

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Résumé Les mâles de Lipara lucens Mg. vivant sur les tiges du Roseau commun (Phragmites communis Trin.) émettent des signaux acoustiques perçus à distance comme une vibration du support par une mouche femelle située sur la même tige de roseau. Les femelles vierges répondent à leur tour à ces signaux par une vibration qui provoque le comportement de découverte chez la mouche mâle. Il est suggéré que ce comportement réduit le temps de découverte du partenaire parce qu'une tige de roseau peut être visitée rapidement par le mâle pour s'assurer de la présence d'une femelle réceptive.

     

Pseudomonas exotoxin fusion proteins are potent immunogens for raising antibodies against P-glycoprotein.

Antibodies to specific regions of human P-glycoprotein have been difficult to obtain. We developed a method to express in E. coli fusions between Pseudomonas exotoxin and specific regions of human P-glycoprotein. We used the polymerase chain reaction to amplify the desired regions of MDR1 cDNA and to introduce appropriate restriction sites. These fragments were cloned into the 3' end of the Pseudomonas exotoxin gene. With this system we produced large amounts of fusion proteins for immunizations, and we obtained positive rabbit antiserum against P-glycoprotein with most of these antigens. We now have a comprehensive panel of polyclonal antibodies against P-glycoprotein. This system should be generally useful to raise antibodies against other eukaryotic proteins that are difficult to prepare in large quantities.     

The physical state of quick-frozen membranes and lipids

Lipid bilayers and biomembranes produce nearly identical calorimeter scans regardless of whether they are slowly cooled under near-equilibrium conditions or rapidly frozen at rates used in freeze-fracture electron microscopy. Except for the melting of ice at 273 K, for both cooling regimens no significant thermal events occur from 100 K to the usual gel to liquid crystal transition. The gel to liquid crystal transition itself is somewhat altered by rapid cooling when bilayers contain mixed lipid species. Combined with X-ray diffraction studies, the results indicate that quickly frozen bilayers are crystalline, but that the crystalline domains are quite small or otherwise disordered. In contrast to the behavior of lipids in bilayers, hexagonal-phase calcium cardiolipid easily forms a glass upon cooling.     

Long-Term Chilling of Young Tomato Plants under Low Light. IV. Differential Responses of Chlorophyll Fluorescence Quenching Coefficients in Lycopersicon Species of Different Chilling Sensitivity

Temperature dependences of chlorophyll fluorescence quenchingcoefficients were studied in the cultivated tomato (Lycopersiconesculentum) and three lines of the chilling-tolerant L.peruvianumfrom different altitudes, i.e. LA 1373 (20 m a.s.l.), LA 2157(1,650 m a.s.l.) and LA 385 (2,400 m a.s.l.). At actinic lightintensity near light saturation of photosynthesis (370 µEm^–2 s^7minus;1), photochemical quenching (qP) increasedwith increasing temperature between 5 and 30°C. The temperature,at which qP reached the numerical value 0.5 [T (qP=0.5)] decreasedby 2.5–4.5°C after a chilling treatment of 14 daysat 10°C in L. peruvianum, indicating acclimation of thephotosynthetic dark reactions in this species. The final T (qP=0.5)attained after chilling could be arranged in the order L.esculentum>LA1373>LA 2157>LA 385. The fast relaxing non-photochemicalquenching (qN) component (qf, consisting mainly of energy-dependentquenching, qE) exhibited minima near the optimum temperaturefor photosynthesis. These minima shifted to lower temperaturesupon chilling in L. peruvianum. Photoinhibitory quenching (ql)was unaffected by chilling in the high altitude lines, but-increasedstrongly in LA 1373 and L. esculentum. Under low actinic light(40 µE m^–2 s^–1), temperature dependences ofqP and qN were nearly identical in L. esculentum and LA 385and revealed abrupt changes at approx. 8°C. It is concludedthat qP and ql, measured after defined chilling treatments,are valuable screening parameters for chilling tolerance inearly growth stages of Lycopersicon plants. (Received November 2, 1993; Accepted February 28, 1994)     

Effects of High-Intensity Swimming on Lung Inflammation and Oxidative Stress in a Murine Model of DEP-Induced Injury

Studies have reported that exposure to diesel exhaust particles (DEPs) induces lung inflammation and increases oxidative stress, and both effects are susceptible to changes via regular aerobic exercise in rehabilitation programs. However, the effects of exercise on lungs exposed to DEP after the cessation of exercise are not clear. Therefore, the aim of this study was to evaluate the effects of high-intensity swimming on lung inflammation and oxidative stress in mice exposed to DEP concomitantly and after exercise cessation. Male Swiss mice were divided into 4 groups: Control (n = 12), Swimming (30 min/day) (n = 8), DEP (3 mg/mL—10 μL/mouse) (n = 9) and DEP+Swimming (n = 8). The high-intensity swimming was characterized by an increase in blood lactate levels greater than 1 mmoL/L between 10th and 30th minutes of exercise. Twenty-four hours after the final exposure to DEP, the anesthetized mice were euthanized, and we counted the number of total and differential inflammatory cells in the bronchoalveolar fluid (BALF), measured the lung homogenate levels of IL-1β, TNF-α, IL-6, INF-ϫ, IL-10, and IL-1ra using ELISA, and measured the levels of glutathione, non-protein thiols (GSH-t and NPSH) and the antioxidant enzymes catalase and glutathione peroxidase (GPx) in the lung. Swimming sessions decreased the number of total cells (p<0.001), neutrophils and lymphocytes (p<0.001; p<0.05) in the BALF, as well as lung levels of IL-1β (p = 0.002), TNF-α (p = 0.003), IL-6 (p = 0.0001) and IFN-ϫ (p = 0.0001). However, the levels of IL-10 (p = 0.01) and IL-1ra (p = 0.0002) increased in the swimming groups compared with the control groups, as did the CAT lung levels (p = 0.0001). Simultaneously, swimming resulted in an increase in the GSH-t and NPSH lung levels in the DEP group (p = 0.0001 and p<0.002). We concluded that in this experimental model, the high-intensity swimming sessions decreased the lung inflammation and oxidative stress status during DEP-induced lung inflammation in mice.     

Regret on Choice of Colorectal Cancer Screening Modality Was Associated with Poorer Screening Compliance: A 4-Year Prospective Cohort Study

Purpose

Very few studies examined the issue of regret on choosing colorectal cancer (CRC) screening tests. We evaluated the determinants of regret and tested the hypothesis that regret over screening choices was associated with poorer screening compliance.

Methods

A bowel cancer screening centre invited all Hong Kong citizens aged 50-70 years who were asymptomatic of CRC to participate in free-of-charge screening programmes. Upon attendance they attended health seminars on CRC and its screening, and were offered an option to choose yearly faecal immunochemical test (FIT) for up to four years vs. one direct colonoscopy. They were not allowed to switch the screening option after decision. A self-administered, four-item validated survey was used to assess whether they regretted over their choice (> 2 = regretful from a scale of 0 [no regret]-5 [extreme regret]). A binary logistic regression model evaluated if initial regret over their choice was associated with poorer programme compliance.

Results

From 4,341 screening participants who have chosen FIT or colonoscopy, 120 (2.8%) regretted over their decision and 1,029 (23.7%) were non-compliant with the screening programme. Younger subjects and people who felt pressure when making their decision were associated with regret. People who regretted their decision were 2.189 (95% C.I. 1.361-3.521, p = 0.001) times more likely to be non-compliant with the programme.

Conclusions

This study is the first to show that regret over the initial CRC screening choice was associated with later non-compliance. Screening participants who expressed regret over their choice should receive additional reminders to improve their programmatic compliance.     

SEASONAL MODULE DYNAMICS OF TURBINARIA TRIQUETRA (FUCALES,PHAEOPHYCEAE) IN THE SOUTHERN RED SEA1

Module dynamics in the fucoid alga Turbinaria triquetra (J. Agardh) Kützing were studied on a shallow reef flat in the southern Red Sea. Seasonal patterns in thallus density and size were determined, and the initiation, growth, reproduction, and shedding of modules were studied using a tagging approach. The effects of module density and module/thallus size on module initiation, growth, reproduction, and shedding were analyzed, and the occurrence of intraspecific competition among modules was examined. Seasonal variation occurred mainly at the modular level. There was a restricted period of new module formation in the cooler season, followed by fast growth and reproduction, massive shedding of modules from the end of the cooler season onward, and strongly reduced biomass in summer. There was no evidence of suppressed growth in small modules due to intraspecific competition. Module density and thallus/module size had opposite effects on elongation rates. High module densities enhanced maximum elongation rates (fastest‐growing module per thallus), resulting in longer thalli. On the other hand, elongation rates decreased and tissue loss increased with increasing module length. Reproduction had no clear effect on elongation rates, indicating that there was no direct trade‐off between reproduction and growth. The apparent size‐dependence of reproduction was due to delayed fertility in young modules. Module initiation and shedding were independent of module density. Shedding was also independent of module size and reproductive status. We conclude that seasonal changes in the environment affect module initiation, growth, reproduction, and shedding, whereas density and size‐dependent processes mainly affect growth rates.